Difference between External and Internal Respiration | Zoology

The upcoming discussion will update you about the difference between external and internal respiration in animals.

Difference # External Respiration:

1. It is a physical pro­cess in which oxygen (O₂) is absorbed and carbon dioxide (CO₂) is given out.

2. Enzymes do not play any role in the process.

3. Restricted to respi­ratory organs only.

4. Respiratory struc­tures are body sur­face, gills, lungs, etc. exposed to the sur­roundings.

5. Sites of gaseous ex­change—moist respi­ratory surfaces; in­flow of O₂ and out­flow of CO₂ occurs through plasma membrane by passive diffusion.

6. Partial pressure of O₂ in the surround­ings determines the rate of O₂ diffusion.

Difference # Internal Respiration:

1. It is a chemical re­action in which oxy­gen (O₂) combines with carbohydrates, fatty acids and amino acids (biological oxi­dation), producing carbon dioxide (CO₂), water and energy.

2. The whole process is enzyme controlled.

3. It takes place in all living cells.

4. Respiration occurs within the cells.

5. Sites of reaction— cystosole of the cell and mitochondria; O₂ and CO₂move in and out of the cell through plasma membrane by passive diffusion.

6. Pressures of O₂ and CO₂ inside the cell and interstitial fluid determine the rate of diffusion of the gases and CO₂ concentra­tion in blood influ­ences the release of O₂ from oxyhaemo­globin (HbO₂).